Process for preparing hydrocarbonaceous products from coal



Feb. 4, 1964 E. GORIN ETAL PROCESS FOR PREPARING HYDROCARBONACEOUS PRODUCTS FROM COAL Filed March 22, 1961 WASTE GAS TAR RELATIVELY DEVOLATILIZATION FINE COAL 10x 30} 1 ZONE DRYING, PREHEATING 4 6 5 8.- SEPARATION 22 ZONE RESIDUE 43 42- L RELATIVELY CHAR COARSE COAL SOLVENT EXTRACTION SEPARAT'ON 1 ZONE ZONE COMMINUTED 34 Q COAL GAS 44 I 6. 1 SOLVENT EXTRACT RELATIVELY I24 FINE COAL SECONDARY WASTE GAS CYCLONES H2 PRIMARY CYCLONE COMMINUTED COAL u Illllllll lllllllllllllll RELATIVELY COARSE COAL FIG.

RELATIVELY FINE COAL INVENTORS EVERETT GORIN MARTIN B. NEUWORTH BY THEIR ATTORNEY United States l atent Cfiice 3 ,120,474 Patented Feb. 4, 19M;

PROCESS FGR PREPARKNG HYDRUQARBONA- CEGUS PRGDUQTS FRQM CBAL Everett Gorin and Martin B. Neuworth, Pittsburgh, Pa,

assignors to Consolidation Coal Company, Pittsburgh, Pa, a corporation of Pennsylvania Filed Mar. 22, that, Ser. No. $7,494

7 Ciairns. (Ql. 292-111) This invention relates to a proces for the conversion of coal to valuable hydrocarbonaceous products.

This application is a continuation-in-part of our copending application Serial No. 82,909, filed January 16, 1961, which is a continuation-in-part of our application Serial No. 702,632, filed December 13, 1957, now abandoned, each of the applications being assigned to the assignee of the present invention.

Numerous processes have been developed for converting coal to valuable hy-drocarbonaceous products, primarily hydrocarbonaceous liquid fuels such as gasoline. Relatively few of the processes, however, have been of any success commercially, particularly the coal-to-gasoline schemes. The Germans made gasoline from coal during World War II, but in view of the circumstances, economic considerations were of little consequence. In this country, a commercial coal-to-gasoline plant has yet to be realized.

One method which the Germans as well as others have used to convert coal to valuable hydrocarbonaceous products is a process which includes a solvent extraction treatment as one of the steps within the over-all process. The primary purpose of a solvent extraction treatment is to convert coal to extract, which under certain circumstances is more amenable to further processing than the original coal. The solvent extraction processes generally comprise initially subjecting the coal to solvent extraction to obtain a mixture of extract and undissolved coal, i.e., residue. Normally, essentially all of the coal is converted to extract. The extract is separated from any undissolved coal, i.e., residue, that remains, and the extract is then subjected to further treatment to obtain the more valuable hydrocarbonaceous products.

in our copending application Serial No. 82,909, a new process for converting coal to valuable hydrocarbonaceous liquids is described. In contrast to the previous solvent extraction schemes, our process does not comprise extracting substantially all of the coal, but comprises extracting only a portion of the coal. The extract is separated from the residue, and the residue is then subjected to treatment in a conventional type fluidized low temperature carbonization zone.

In solvent extraction processes, the coal is generally comminuted prior to introducing the coal into the solvent extraction zone. All of the comminuted coal is then introduced into the extraction zone. When coal is to be treated in a solvent extraction zone, it is highly desirable, economically, that a continuous solvent extraction unit be employed. The coal is generally introduced into the continuous extraction zone in the form of a coal-solvent slurry, the solvent generally being the hydrocarbonaceous solvent used to extract the coal. In order to maintain the coal in the slurry, however, it is necessary that the coal particles employed be limited to a certain top size. The particular size consist of the coal particles is dependent primarily on the practicality of conveying them in the form of a slurry to the extraction zone. For the above reason, it is desirable to limit the size of the largest coal particle to less than about Ms inch.

An additional reason for comminuting the coal is that the residue from the solvent extraction zone may be subjected to carbonization in a fluidized low temperature carbonization zone without further reduction in particle size.

The coal feedstream to the solvent extraction zone generally comprises coal having a size consist in the range of about 8 x (l mesh Tyler Standard screen, and preferably 14 x 0 mesh Tyler Standard screen. The coal is usually cornrnin'uted prior to admixing the coal with the solvent.

Where coal is prepared by comminution in conventional crushing and grinding equipment, the material will contain a usual random distribution of particles of all sizes down to ultra-fines having diameters which are measured in microns. For example, a typical differential and cumulative screen analysis of a comrninuted coal suitable for treatment by fluidized low temperature carbonization and for conveying in the form of a slurry is presented in the following Table I.

TABLE I.DI FFERENTIAL AND CUMULATIVE SCREEN ANALYSIS OF COMMINUTED AG- GLOMERATING COAL As a result of our recent research, we have found that a number of advantages exists if only a portion of the comminuted coal is introduced into the solvent extraction zone. We have found that only a particular portion of the comminuted coal should be introduced into the extraction zone, while the remaining cornminuted coal should be treated in another manner, as will be hereinafter more fully discussed.

The primary object of this invention is to provide a process for the conversion of coal to valuable hydrocarbonaceous products.

Another object of this invention is to provide a process for the conversion of coal to valuable hydro-carbonaceous products wherein a solvent extraction zone is included as one of the process steps.

A further object of this invention is to provide a process including a solvent extraction zone for the conversion of coal to valuable hydrocarbonaceous products wherein particular portions of the comminuted coal feedstream are separately treated in a novel manner.

in accordance with our invention, corn-minuted coal is separated into at least two fractions, a relatively fine fraction and a relatively coarse fraction. The relatively coarse fraction consists of coal particles of larger median size than the coal particles contained in the relatively fine fraction, hereinafter more fully explained. At least a portion of the relatively coarse coal fraction is. subjected to solvent extraction with a hydrocarbonaceous solvent under conditions such that a portion of the coal is dissolved, i.e., extracted. The resulting mixture of extract and undissolved coal (the undissolved coal being hereinafter referred to as residue) is separated in a conventional type separation zone. At least a portion of the residue and at least a point of the relatively fine coal fraction are subsequently subjected to devol atilization, e.g., carbonization, to yield a tar distillate. The extract and the tar distillate are thereafter recovered for further processing.

In the preferred embodiment of this invention, the comvrniriuted coal feedstream is separated into the relatively Discussion In order to understand and fully appreciate the present invention, a brief discussion of certain facts implicit in the invention follows.

In most coal conversion processes wherein a continuous solvent extraction zone is employed, the extract obtained from the extraction zone is generally separated from the residue, if any is present, prior to further treatment of the extract. Normally, the separation zone is a conventional type filtration zone. It is economically desirable to employ other conventional type separation zones, such as a hydroclone, centrifuge, or sedimentation zone, in place of the filtration zone. Unfortunately, it has been found that adequate separation of the residue from the extract can usually be eiiected only with a filtration zone. However, filtration rates which are desirable in a commercial plant filtration zone are normally not attained.

The extraction products consist of a slurry of fine residue particles in a solution of the extraction solvent and the extract, the slurry having a relatively high density and viscosity. The fine residue particles accordingly have a tendency to remain suspended in the extract-solvent solution and, in some instances, enter the filter septum and blind the interstices thereby lowering the filtration rate. T o complicate matters even further, it is known that when more than about 40 percent by weight of the moisturefree and ash-free, i.e., MAP, coal is extracted, the individual coal particles tend to degrade. Thus, filtration of the resulting extraction products becomes even more difficult.

We have found that the filtration rate of the extraction products may be improved by eliminating the relatively fine portion of the comminuted coal fed to the solvent extraction zone. Obviously, this will minimize the concentration of fine residue particles in the extraction product, thereby enhancing filtration and in many instances enabling other conventional type separation zones to be employed. It i not enough, however, just to remove the fine coal particles from the feedstream to the extraction zone, since the fine coal particles are also capable of being converted to valuable hydrocarbonaceous products. It is the combination of minimizing the filtration problem and still converting the fine coal particles to valuable hydrocarbonaceous products which is the important feature of our invention. It is economically prohibitive to convert only the relatively coarse fraction of coal to the more valuable hydrocarbonaceous products.

A previously mentioned, a carbonization zone is included in the process described in our ccpending application Serial No. 82,909. In view of this, and since it is not economical to discard the relatively fine coal fraction, it was decided to subject the relatively fine coal fraction to carbonization in admixture with the residue. We discovered that the relatively fine coal particles can be processed to yield a greater quantity of recoverable distillate tar products per unit weight than that recovered not only from the residue particles but also from the larger coal particles that had not heen extracted. The higher yield of tar results from the fact that pretreating the fine coal fraction prior to carbonization is not required, as explained below. Thus, in addition to the advantage gained by eliminating the coal fines from the filtration zone, there is a corollary advantage in subjecting the coal fines to oarbonization.

It is preferred to use a fluidized low temperature carbonization zone as the devolatilization zone. However, when the coal employed in the process is a highly caking coal, it i generally necessary to prcoxidize the coal to prevent the particles from agglomerating in the fluidized low temperature carbonization zone. The preoxidation treatment, unfortunately, severely reduces the tar yield.

It has been discovered that relatively fine coal particles possess a much lower caking tendency than coarse coal in fluidized low temperature carbonization processing. Since the larger particles of coal can be rendered substantially non-agglomerative under fluidized low temperature carbonization conditions (via solvent extraction as disclosed in our copending application Serial No. 82,909), the untreated coal fines can be admixed therewith to pro vide a feed material which is operable under fluidized low temperature carbonization conditions.

It is to be understood that by the phrases relatively coarse and relatively fine, we intend to distinguish two fractions of the coal feedstream which differ significantly in median particle size. The relatively fine fraction could comprise principally particles capable of passing through a 200 mesh screen; whereas the corresponding relatively coarse fraction would comprise the original coal feedstrearn from which the relatively fine fraction had been removed. The relatively coarse fraction, of course, may contain significant quantities of particles capable of pasing through a 200 mesh screen, and the relatively fine fraction could similarly contain significant quantities of particles too large to pass through a 200 mesh screen.

Preferred Embodiment The following, with reference to FIGURE 1 of the drawings, is a description of the preferred embodiment of this invention. The process of the preferred embodiment comprises introducing comminuted coal into a combination drying, preheating, and separation zone 10 wherein the relatively fine fraction of the coal is separated from the relatively coarse fraction; introducing the relatively coarse fraction into a continuous solvent extraction zone 34 wherein the coal is extracted to produce a mixture of extract and residue; separating the extract and residue mixture in a separation zone 40; and introducing the relatively fine coal fraction and the residue into a devolatilization zone 46.

Drying, Preheatilzg, and Separation Zone Comminuted coal, preferably highly caking, high volatile bituminous coal such as Pittsburgh Seam coal, is introduced into a drying, preheating, and separation zone 10 via a conduit 12. The coal had been previously com minuted to a size consist in the range of about 8 x 0 mesh Tyler Standard screen, and preferably in the range of about 14 x 0 mesh Tyler Standard screen. A fluidized bed 14 of fiuidizable size coal particles is established in the zone 10 under the influence of gases flowing upwardly at a velocity of about 0.5 to 2.5 feet per second through the zone from a conduit 16. Where hot gases are em ployed for eflecting drying and preheating, they are provided in sufficient quantity and at a temperature sufiiciently high to remove moisture from the coal particles and to heat the dried particles to an elevated temperature in order to minimize the heat input requirements for further coal processing.

Alternatively, heating tube bundles or heating coils 13 may be embedded within the fluidized bed 14 to provide the heat needed for drying and preheating. A heat exchange medium such as hot oil, hot sand and the like may be supplied to the heating element 18 through a conduit 20 and removed for reheating through a conduit 22. Exit temperature of the coal particles from the zone 10 should be from about 120 C. to 340 C., preferably from about 200 C. to 290 C. The coal particles should not be subjected to temperatures at which agglomeration will occur during the drying and preheating step. The gases rise through the fluidized bed 14 and are recovered from the zone via a conduit 24 with substantial quantities of relatively fine coal particles entrained therein. The en trained relatively fine coal particles are separated from the gases in a conventional type gas-solids separation device 26 such as a cyclone. Solids-free gases, i.e., waste gases, are eliminated from the cyclone 26 via a conduit 23. Relatively fine coal particles are recovered from the cyclone 26 via a conduit 30. Regulation of the upward linear velocity of the hot gases in the drying, preheating, and separation zone 10 permits control of the fraction of the comminuted coal feedstream which will be entrained and recovered via the conduit 24 as the relatively fine coal fraction.

Referring again to the drying, preheating, and separation zone 10, the relatively coarse particles from the comminuted coal feedstrearn are not entrained in the fluidizing gases and may be withdrawn from the zone 10 via a conduit 32. The quantity of relatively fine coal particles which are separately treated should be at least about 10 percent by weight and preferably at least about percent by weight of the coal feedstream. The quantity of relatively coarse particles which are subjected to solvent extraction should be at least about 50 percent by weight of the coal feedstream.

In place of the zone 10, any conventional type separation zone may be employed for separating the relatively fine coal fraction from the relatively coarse coal fraction. However, in view of the fact that the coal must be dried and preheated for further treatment in the process of this invention, the above method for simultaneously drying, preheating, and separating the comminuted coal is desirable.

Solvent Extraction Zone The relatively coarse coal fraction withdrawn from the zone 10 via the conduit 32 is introduced into a conventional type solvent extraction zone 34 in admixture with a hydrocarbonaceous solvent introduced into the zone 34 via a conduit 36. Commercially, it is desirable that the overall process be continuous; however, if desired, batch or semi-continuous operation may be employed. As previously mentioned, if continuous operation is employed, the coal being introduced into the solvent extraction zone is premixed with the solvent and then introduced into the extraction zone 34 in the form of a coal-solvent slurry.

The coal and solvent react in the extraction zone so that at least a portion of the coal is extracted, the extraction products being withdrawn via a conduit 33. The depth of coal conversion, i.e., the amount or" coal that is extracted, is dependent primarily on the purpose of the over-all conversion process. If it is desired only to decake the coal for subsequent treatment in a fluidized low temperature carbonization zone, then at least 10 percent by weight (on a MAP basis) of the relatively coarse coal fraction introduced into the extraction zone must be extracted. Such a process is described more fully in our copending application Serial No. 82,909. However, if it is desired to make hydrocarbonaceous liquid products suitable for conversion to gasoline, then the extraction treatment should be such that between about 50 to 70 percent by weight (on a MAP basis) of the relatively coarse fraction introduced into the extraction zone is converted to extract. Such a process is described in the copending application by Everett Gorin, Serial No. 61,518, filed October 10, 1960, now U.S. Patent No. 3,018,242.

The solvent extraction process may be any of the processes commonly employed by those skilled in the art, e.g., at a temperature in the range of about 300 C. to 500 C., a pressure in the range of one p.s.i.g. to 6500 p.s.i.g., a residence time in the range of one minute to 120 minutes, a solvent-to-coal ratio of from 0.5/1 to 4/1, and, if desired, a catalyst or up to 50 standard cubic feet of hydrogen per pound of coal feed may be used. The particu- 6 lar conditions of extraction will be determined by the depth of coal conversion that is desired.

Suitable solvents for the coal in the extraction step are those which are predominantly polycyclic hydrocarbons. These are usually aromatic hydrocarbons which may be partially or completely hydrogenated, including naphthenic hydrocarbons, which are liquid under the temperature and pressure of extraction. Mixtures of these hydrocarbons are generally employed, and are derived from intermediate or final steps of the process of this invention. Those hydrocarbons or mixtures thereof boiling between 260 C. and 425 C. are preferred. Examples of suitable solvents are tetrahydronaphthalene, Decalin, biphenyl, methylnaphthalene, and dimet-hylnaphthalene. Other types of coal solvent may be added to the above-mentioned types for special reasons, but the resulting mixture should be predominantly of the types mentioned, that is, should constitute more than 50 percent by weight of the solvent used. Examples of additive solvents are the phenolic compounds, such as phenol, cresols, and xylenols.

S eparatz'onl Zone Substantially all of the extract and the solvent are separated from the residue in a conventional type separation zone 40, which is preferably a filltration zone. If desired, however, a cyclone, centrifuge, or a conventional type settling zone may be employed in place of the filtration zone. The residue, substantially free of solvent and extract, is withdrawn from the separation zone 4 via a conduit 42, while a mixture of the extract and the solvent is withdrawn via a conduit 44.

Devolatilization Zone At least a portion of the residue withdrawn from the separation zone 4t} via the conduit 42 and at least a portion of the relatively fine coall fraction withdrawn from the cyclone as are introduced into a conventional type devolatilization zone 46 which is maintained at a temperature in the range of about 425 C. to 760 C. It is usually desirable to premix the fine coal and the residue to minimize any tendency of the feed coal to agglomerate. Preferably, the zone 46 is a fluidized low temperature carbonization zone; however, if desired, other conventional devola tilization zones may be employed, e.g., a rotary killn. Hydrocarbonaceous solids, i.e., char, are withdrawn from the zone 46 via a conduit 48, While tar vapors and any solvent that may have adhered to the residue subsequent to the separation zone 4%) are withdrawn via a conduit 50. If necessary, the tar vapors and the solvent are freed of any entrained solids, before being subsequently treated, by any suitable means such as an electrostatic precipitator or a m-icrometallic filter.

The tar vapors are subsequently condensed so that a distillate tar is obtained. The distillate tar may be introduced in combination with the extract obtained from the separation zone 40 into a conventional type hydrocracking zone (not shown) to produce valuable hydrocarbonaceous liquids suitable for conversion to gasoline in a conventional type gasoline refining plant. However, when less than about 50 percent by weight (MAF basis) of the relatively coarse fraction is converted to extract, it is economically desirable to utilize the extract in applications other than for hydrocracking to gasoline, for example, as a coker feedstock.

Due to the fact that the relatively fine coal particles are subjected directly to devolatilization without any pre vious solvent extraction, a fraction of the distillate tar recovered from the devolatilization zone will be relatively rich in tar acids, i.e., cresols, phenols, and xylenols. These materials are preferably recovered from the tar prior to admixing the tar fraction with the extract.

If desired, a portion of the residue from the separation zone may be employed for other purposes, for example, the residue may be introduced into a conventional type water-gas generator.

EXAMPLE High volatile bituminous coal having the following properties is employed in each of the process sequences of thies example.

Percent volatile matter 39.3 Percent fixed carbon 4-7.7 Percent ash 13.0

Heat of combustion, B.t.u./lo. 12,700 Fischer assay tar yield (percent by weight) 16.6

TABLE II.COMPA=RISON OF YIELDS FOR VARIOUS PROCESS SEQUENCE/S Yields of Liquid ProductsWt. Percent MAP Feed Coal Process Sequence Step Feed (MAF Basis) Wt. Total Percent of Coal Benzene Benzene Ex- Soluble Light Soluble tract Extract Oil Plus or Tar Light Oil A [Extraction 100 Cool 3S. 7 18. S 18.8 lCarbonization..- 59.1 Extraction Residue 0.7 0. 4 7.1

Total Yields in Process 38. 7 25. 5 4 25. 9 Extraction I65.0 Coarse Coalil 25.2 12.2 "5. 1:31. 2 B 38.4 (Extraction .esit ue 4. 4 0. .7 crrbommwn-e 35.0 Fine Coal 8.7 0. 5 9.2

Total Yields in Process 25. 3 0.8 26.1 C Carbonization--. 13. 4 0.8 14. .2

Sequence A.-A sample of the above coal is comrninuted to particles having a size consist in the range of 14 x 0 mesh Tyler Standard screen. The cornminuted coal is subjected to solvent extraction with crude dimethylnaphthalene for one hour at 350 C. Two pounds of solvent are employed for each pound of coal. The resulting mixture of extract and undissolved coal, i.e., residue, is filtered and the recovered residue is then introduced into a fluidized low temperature carbonization zone. The residue is carbonized for minutes at 496 C. Because the residue is substantially non-caking, no treatment such as preoxidation is necessary prior to introducing the residue into the carbonization zone.

Sequence B.A second sample of the same coal is comminuted to particles having a size consist in the range of 14 x 0 mesh Tyler Standard screen. The comminuted coal is introduced into a drying, preheating, and separation zone such as described in the preferred embodiment wherein the comminuted coal is separated by elutriation into a coarse fraction and a fine fraction. The coarse fraction comprises percent by weight of the comrn-inuted coal, and the fine fraction comprises 35 percent by weight of the comminuted coal. The coarse fraction which is substantially all coarser than 200 mesh is subjected to solvent extraction and filtration in the same manner as described in Sequence A. Due to the coarser coal employed in the extraction step, a considerably higher filtration rate than in Sequence A is attained. The residue recovered from the filtration zone is combined with the fine fraction (which substantially all is finer than 200 mesh), and the mixture is subjected to fluidized low temperature carbonization as described in Sequence A. The eaking characteristics of the mixture are sufficiently low, thereby enabling the mixture to be treated in the fluidized carbonization zone without any pretreatment. Thus a maximum yield of tar is obtained from the fine coal fraction.

Sequence C.--A third sample of the above coal is also comminuted as described above, and the comminuted coal is introduced into a fluidized low temperature carbonization zone under the same conditions set forth in The most significant comparison between the three sequences is the total yield of benzene soluble material plus light oil. These materials are the more valuable products on the basis of ease in conversion to valuable hydrocarbonaceous products. The above yields represent close to the maximum that can be achieved without the use of hydrogen, directly or indirectly, for example, by hydrogen transfer from a hydrogen donor solvent.

It is seen that Process Sequences A and B give substan tially higher yields than can be achieved by direct carbonization of the coal. The improvement arises largely from obviating the need for pretreatment of the coal which severely reduces the tar yield.

It is noted that the yields of benzene soluble liquid are substantially the same in Sequences A and B. Economically, however, Process Sequence B is preferred because the extraction step is simplified both by virtue of the higher filtration rate achieved and the fact that the extraction plant is reduced in size.

Alternative Embodiment Referring to FIGURE 2 of the drawings, an alternative embodiment is illustrated for conducting the combined drying, preheating, and separation function.

In FIGURE 2, we have illustrated an alternative embodiment of the means for simultaneously drying, preheating, and separating a coal feedstream employing the so-called flash dryer principle. Comminuted coal is introduced into a coal surge hopper and fed uniformly through a screw conveyor 102 into a flash dryer chimney 104. Hot gases are generated by combustion in la combustion chamber 106 and are passed through a flue 168 into a hot gas charnber 110 which is in open communication at its upper end with the bottom of the flash drying chimney 104 at sufficient velocity to carry the coal particles from the screw conveyor 102 upwardly therethrough. The hot gases and suspended solids are introduced into an inetficient primary cyclone separator 112 which removes the more readily separable coal particles from suspension in the hot gases for recovery through a conduit 1 14. Generally these particles recovered through the conduit 114 will be the relatively coarse particles of the coal feedstream. The hot gases with entrained particles of coal which are more :ditficult to separate leave the cyclone separator 112 via a conduit 116 and the gas passes sequentially through a plurality of more efficient secondary cyclone separators 118 which will remove the more-difiicult-to-separate particles of relatively fine coal. These particles of relatively fine coal are recovered through the cyclone diplegs 120 and combined in a manifold conduit 122. Following lpassage through the plurality of efiicient secondary cyclone separators, the solids-free hot gases are removed from the system through a conduit 124.

The relatively coarse coal in the conduit 114 thereupon may be treated as are the sol-ids in the conduit 32 shown in FIGURE 1. The relatively fine coal in the manifold conduit 122 may (be treated as the relatively fine coal in the conduit 30 of FIGURE 1.

According to the provisions of the patent statutes, we have explained the principle, preferred construction, and mode or operation of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. A method for preparing hydrocarbon-aceous products from coal which comprises (a) separating said coal into two fractions, comprising a relatively coarse fraction and a relatively fine fraction, said relatively coarse fraction comprising coal particles of larger median size than the coal particles comprising said relatively fine fraction,

(1)) subjecting at least a portion of said relatively coarse fnaction to solvent extraction under conditions such that at least a portion of said coal is extracted, whereby an extract and an undissolved residue are obtained,

() separating the extract from the residue, and

(d) thereafter devolatilizing at least a portion of said relatively fine coal fraction in admixture with at least a portion of said residue.

2. A method for preparing hydrocarbonaceou-s products from coal which comprises (a) separating said coal into two fractions, comprising a relatively coarse fraction and a relatively fine fraction, said relatively coarse fraction comprising coal particles of larger median size than the coal particles comprising said relatively fine fraction,

(b) subjecting at least a portion of said relatively coarse fraction to solvent extraction under conditions such that at least a portion of said coal is extracted, whereby an extract and an undissolved residue are obtained,

(0) separating the extract from the residue, and

(d) thereafter devolatilizing at least a portion of said relatively fine coal fraction in admixture with at least a portion of said residue in a fluidized low temperature carboniz-ation zone under conditions to yield a tar distillate.

3. A method for preparing hydrocarbonaceous products from caking bituminous coal which comprises (a) separating said coal into two fractions, comprising a relatively coarse fraction and a relatively fine fraction,

(1)) partially extracting at least a portion of said relatively coarse fraction with a hydrocarbonaceous solvent to yield a solvent solution and a substantially non-agglomerating undissolved coal,

(0) separating the undissolved coal from the solvent solution, and

'(d) thereafter de'volatilizing at least a portion of said undissolved coal and at least a portion of said relatively fine fraction in a fluidized state.

4. A method for preparing hydrocarbonaceous products firom coal which comprises (a) separating said seal into two firactions, comprising a relatively coarse fraction and a relatively fine frac- 5 tion, said relatively coarse fraction comprising coal particles of larger median size than the coal particles comprising said relatively fine fraction, (12) subjecting at least a portion of said relatively coarse fraction to solvent extraction under conditions such that at least about percent by weight of the 10 coal on an basis is extracted, whereby an extract and an undissolved residue are obtained, (0) separating the extract from the residue, and (d) thereafter devolatilizing at least a portion of said 15 relatively fine coal fraction in admixture with at least a portion of said residue in a fluidized low temperature carbonization zone under conditions to yield a tar distillate. 5. A method for preparing hydrocarbonaceous products from coal which comprises (a) separating said coal into two fractions, comprising a relatively coarse fraction which contains at least 50 percent of said coal and a relatively fine fraction which contains at least 10 percent of said coal, said relatively coarse fraction comprising coal particles of larger median size than the coal par ticles comprising said relatively fine fraction,

(11) subjecting at least a portion of said relatively coarse fraction to solvent extraction under conditions such that at least a portion of said coal is extracted whereby an extract and an undissolved residue are obtained,

(c) separating the extract from the residue, and

(d) thereafter devolatilizing at least a portion of said relatively fine coal traction in admixture with at least a portion of said residue.

6. A method for preparing liquid hydrocarbonaceous products from eaking bituminous coal which comprises (a) comminuting the coal to a fluidizable size,

([2) separating therefrom a relatively fine fraction containing substantially 'all the particles capable of passing through a 200 mesh screen and a relatively coarse traction substantially free Olf particles capable of passing through a 200 mesh screen,

(0) subjecting at least a portion of said relatively coarse [fraction to solvent extraction under conditions such that at least a portion of said coal is extracted, whereby an extract and an undissolved residue are obtained,

(d) separating the extract from the residue, and

(e) thereafter devolatilizing at least a portion of said relatively fine coal fraction in admixture with at least a portion of said residue.

7. A method for preparing liquid hydrocarbonaceous products from caking bituminous coal which comprises (a) comminuting the coal to a fluidizable size,

(b) separating therefrom a relatively fine fraction containing substantially all the particles capable of passing through a 200 mesh screen and a relatively coarse fraction substantially free or par-ticles capable of passing through a 200 mesh screen,

(c) admixing at least a portion of the said relatively coarse fraction with a liquid hydrocanbonaceous solvent,

(d) maintaining the said portion of the relatively coarse [fraction and the said solvent in admixture until about 10 percent by weight of the coal on an MAF basis is dissolved in said solvent, whereby an undissolved coal residue and a solvent solution are obtained,

(e) recovering the solvent solution of dissolved coal separately from the undisssolved coal residue,

1(f) introducing at least a portion of the undissolved relatively coarse coal residue into a thermal devolatil-ization zone maintained at a temperature from 800 to 1400" F.,

4 1 A :1 12 (g) introducing at least a portion of said relatively References Cited in the file of this patent fine fraction into said thermal devolatilization zone, UNITED STATES PATENTS (l1) malntainmg the coal and undissolved coal residue in said thermal devolatilization zone in a fluidized 1,280,178 Day 1918 state until its evolution of volatile materials subr 2,353,752 Otto July 1944 stantially ceases and a char residue remains, a 2534728 Nelson et 1950 (i) recovering said char residue, and 2,637,683 Kassffl May 1953 3,018,242 Gorin Jan. 23, 1962 (j) separately recovering the evolved volatile materials. 

1. A METHOD FOR PREPARING HYDROCARBANACEOUS PRODUCTS FROM COAL WHICH COMPRISES (A) SEPARATING SAID COAL INTO TWO FRACTIONS, COMPRISING A RELATIVELY COARSE FRACTION AND A RELATIVELY FINE FRACTION, SAID RELATIVELY COARSE FRACTION COMPRISING COAL PARTICLES OF LARGER MEDIAN SIZE THAN THE COAL PARTICLES COMPRISING SAID RELATIVELY FINE FRACTION, (B) SUBJECTING AT LEAST A PORTION OF SAID RELATIVELY COARSE FRACTION TO SOLVENT EXTRACTION UNDER CONDITIONS SUCH THAT AT LEASST A PORTION OF SAID COAL IS EXTRACTED, WHEREBY AN EXTRACT AND AN UNDISSOLVED RESIDUE ARE OBTAINED. (C) SEPARATING THE EXTRACT FROM THE RESIDUE, AND (D) THEREAFTER DEVOLATILIZING AT LEAST A PORTION OF SAID RELATIVELY FINE COAL FRACTION IN ADMIXTURE WITH AT LEAST A PORTION OF SAID RESIDUE. 